Dr. River and their Blasters. They are just some of the many weapons they created to help protect monsters from humans, and better their odds if another war happened. Eventually they give three of the blasters to others for summons and keep one for themself.
I like to believe that Cruz would be the kinda person to tease (or ironically compliment) Jackson every chance she gets. Which would get the usually cool and collected Jackson all annoyed and flustered.